Filament for incandescent lamps or similar articles



`June 14 1927.

c. SEVERIN FILAMENTFOR INCANDESCENT LAMPS OR `SIMILAR ARTICLES FiledD90. 4. 1926 C/l. TURN-STI??? /NCH INS/ENIUH. CARL SE1/:ERIM

H175 TTUHNEX.

'Parental June 14, 1927.

UNITED STATES PATENT OFFICE.

CARL SEvERIN, OF CLEVELAND HEIGHTS, OHIO, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A. CORPORATION F NEW YORK.

FILAMENT FOR IE'CANDESCENT LAMPS OR SIMILAR ARTICLES.

Application led December 4, 1926. Serial No. 152,699.

My invention relates to electric incandescent lamps and similar devicescomprising a filament or other energy translating body and moreparticularly to the said filament or '5 translating body per se. Stillmore particularly my invention relates to coiled aments which have a Uor V shape comprising two straight leg portions connected by a bendportion. l v It is desirable inthe case of coiled filament to have auniform spacing of the turns since this causes the various portions ofthe filament to be heated to a uniform temperature, thus avoiding hotspots. The practice has been to deliver the straight sections of thecoiled filaments to the operator for mounting who, in the process ofmounting, bends the lament in the desired shape. Heretofore in thestraight sectionsof the filament thus ap lied, there has been a uniformspacing o yturns and the mountin causes an ununiform spacing since theben `ing of the filament causes the coils at the bend portion to comecloser together on the inside than do the coils on the extreme ends orleglportions. I have found that by spac- 4 ing t end portions andcomparatively far apart at the intermediate portions of the straightsec- `3o tions of the filament, that coils inside of the bend portionwill be spaced apart substantially the same distance as the coils in thelelportions.

the drawing, Fig. 1 is an elevation of B5 an electric incandescent lampcomprising a filament made in accordance with my invention; Fig. 2 is anenlarged elevation of a mounted filament; and Fig. 3 is a partiallybroken away elevation of a straight section 40 of a lament ready formounting.

In the drawing the filament 10 is of coiled metal, ordinarily tungsten,and is mounted upon the rigid .conducting supports 11-12 which are'united to the leading-in conductors 13-14 sealed into the flattenedportion 15 of the glass stem 16, said stem bein sealed into a lamp whichcomprises the usua vturns e coils more closely together at thel bulb 17and base 18. As shown in Fig. 3, the straight section of filamentconsists of a coil ordinarily of drawn tungsten. The coil is wound witha variable pitch, that is, the spaces of the coil are narrower at theends of the section than in the middle. as indicated in the drawing. Thenumber of per inch runs from one hundred twenty-five at the extreme endsto one hun- Adred at the middle portion. When such a lament'is mountedin the U shape, as shown in Fig. 2, there is substantially uniformspacing of the coils around the inside of the filament. .This result canbe obtained Vfor various sizes of filament. By suitably varying thespacing of the coils, a uniform spacing may be secured in filaments ofvarlous sizes and shapes. 1

What I claim as new and desire to secure by Letters Patent of the UnitedStates, `is,

1. In an electric incandescent lamp or similar device, a coiled filamentcomprlsing two leg portions connected by an intermediate or bend portionand having its coils substantially uniformly spaced from each otheralong the inside the filament.

2. The method of making and mounting bent coiled filaments forincandescent lamps and similar devices which consists in coiling saidfilament with a variable pitch-such that the coils are more .widelyspaced at what is to be a bent ortion, and then bending and mountingsa1d filament on its supports.

3. In the manufacture of incandescent lamps and similardevicescomprising a filament and supports therefor, .the method4 which consistsin coilin said filament with a variable pitch such t at in theintermediate portion of the filament the coils are more widely spacedthan in the end portions, and then mounting said filament on saidsupports so that it assumes a substantially U shape. y

In witness whereof, Iy have hereunto set my hand this 1st day ofDecember,'1926.

CARL SEVERIN.

